간행물
한국재료학회지 KCI 등재 SCOPUS Korean Journal of Materials Research
- 발행기관 한국재료학회
- 자료유형 학술지
- 간기 월간
- ISSN 2799-8525 (Print)2799-8681 (Online)
- 수록기간 1991 ~ 2024
- 주제분류 공학 > 재료공학 공학 분류의 다른 간행물
- 십진분류KDC 530DDC 620
권호리스트/논문검색
제23권 제8호 (2013년 8월) 9건
1.
2013.08
구독 인증기관 무료, 개인회원 유료
Atomic layer deposition(ALD) is a promising deposition method and has been studied and used in many different areas, such as displays, semiconductors, batteries, and solar cells. This method, which is based on a self-limiting growth mechanism, facilitates precise control of film thickness at an atomic level and enables deposition on large and three dimensionally complex surfaces. For instance, ALD technology is very useful for 3D and high aspect ratio structures such as dynamic random access memory(DRAM) and other non-volatile memories(NVMs). In addition, a variety of materials can be deposited using ALD, oxides, nitrides, sulfides, metals, and so on. In conventional ALD, the source and reactant are pulsed into the reaction chamber alternately, one at a time, separated by purging or evacuation periods. Thermal ALD and metal organic ALD are also used, but these have their own advantages and disadvantages. Furthermore, plasma-enhanced ALD has come into the spotlight because it has more freedom in processing conditions; it uses highly reactive radicals and ions and for a wider range of material properties than the conventional thermal ALD, which uses H2O and O3 as an oxygen reactant. However, the throughput is still a challenge for a current time divided ALD system. Therefore, a new concept of ALD, fast ALD or spatial ALD, which separate half-reactions spatially, has been extensively under development. In this paper, we reviewed these various kinds of ALD equipment, possible materials using ALD, and recent ALD research applications mainly focused on materials required in microelectronics.
5,200원
2.
2013.08
구독 인증기관 무료, 개인회원 유료
Recently, steel structures have increasingly been required to have sufficient deformability because they are subjected to progressive or abrupt displacement arising from structure loading itself, earthquake, and ground movement in their service environment. In this study, high-strength low-carbon bainitic steel specimens with enhanced deformability were fabricated by varying thermo-mechanical control process conditions consisting of controlled rolling and accelerated cooling, and then tensile and Charpy V-notch impact tests were conducted to investigate the correlation between microstructure and mechanical properties such as strength, deformability, and low-temperature toughness. Low-temperature transformation phases, i.e. granular bainite (GB), degenerate upper bainite(DUB), lower bainite(LB) and lath martensite(LM), together with fine polygonal ferrite(PF) were well developed, and the microstructural evolution was more critically affected by start and finish cooling temperatures than by finish rolling temperature. The steel specimens start-cooled at higher temperature had the best combination of strength and deformability because of the appropriate mixture of fine PF and low-temperature transformation phases such as GB, DUB, and LB/LM. On the other hand, the steel specimens start-cooled at lower temperature and finish-cooled at higher temperature exhibited a good low-temperature toughness because the interphase boundaries between the low-temperature transformation phases and/or PF act as beneficial barriers to cleavage crack propagation.
4,000원
3.
2013.08
구독 인증기관 무료, 개인회원 유료
Quantum dots(QDs) with their tunable luminescence properties are uniquely suited for use as lumophores in light emitting device. We investigate the microstructural effect on the electroluminescence(EL). Here we report the use of inorganic semiconductors as robust charge transport layers, and demonstrate devices with light emission. We chose mechanically smooth and compositionally amorphous films to prevent electrical shorts. We grew semiconducting oxide films with low free-carrier concentrations to minimize quenching of the QD EL. The hole transport layer(HTL) and electron transport layer(ETL) were chosen to have carrier concentrations and energy-band offsets similar to the QDs so that electron and hole injection into the QD layer was balanced. For the ETL and the HTL, we selected a 40-nm-thick ZnSnOx with a resistivity of 10Ω·cm, which show bright and uniform emission at a 10 V applied bias. Light emitting uniformity was improved by reducing the rpm of QD spin coating.At a QD concentration of 15.0 mg/mL, we observed bright and uniform electroluminescence at a 12 V applied bias. The significant decrease in QD luminescence can be attributed to the non-uniform QD layers. This suggests that we should control the interface between QD layers and charge transport layers to improve the electroluminescence.
4,000원
4.
2013.08
구독 인증기관 무료, 개인회원 유료
Transparent and conducting thin films of Ta-doped SnO2 were fabricated on a glass substrate by a pulse laserdeposition(PLD) method. The structural, optical, and electrical properties of these films were investigated as a function ofdoping level, oxygen partial pressure, substrate temperature, and film thickness. XRD results revealed that all the deposited filmswere polycrystalline and the intensity of the (211) plane of SnO2 decreased with an increase of Ta content. However, theorientation of the films changed from (211) to (110) with an increase in oxygen partial pressure (40 to 100mTorr) and substratetemperature. The crystallinity of the films also increased with the substrate temperature. The electrical resistivity measurementsshowed that the resistivity of the films decreased with an increase in Ta doping, which exhibited the lowest resistivity(ρ~1.1×10−3Ω·cm) for 10wt% Ta-doped SnO2 film, and then increased further. However, the resistivity continuouslydecreased with the oxygen partial pressure and substrate temperature. The optical bandgap of the 10wt% Ta-doped SnO2 filmincreased (3.67 to 3.78eV) with an increase in film thickness from 100-700nm, and the figure of merit revealed an increasingtrend with the film thickness.
4,000원
5.
2013.08
구독 인증기관 무료, 개인회원 유료
There is increasing interest in zirconia as a dental material due to its aesthetics, as well as the exceptionally high fracture toughness and high strength that are on offer when it is alloyed with certain oxides like yttria. In recent years, many solution based chemical synthesis methods have been reported for synthesis of zirconia, of which the sol-gel method is considered to be best. Here, we synthesize zirconia by a sol gel assisted precipitation method using either PEG or PVA as a stabilizing agent. Zirconia sol is first synthesized using the hydrothermal method. We used NaOH as the precipitating agent in this method because it is easy to remove from the final solution. Zirconium and yttrium salts are used as precursors and PEG or PVA are used as stabilizers to separate the metal ions. The resulting amorphous zirconia powder is calcined at 900˚C for 2 h to get crystallized zirconia. XRD analysis confirmed the partially stabilized zirconia synthesis in all the synthesized powders. SEM was taken to check the morphology of the powder synthesized using either PEG or PVA as a stabilizing agent and finally the transparency was calculated. The results confirmed that the powder synthesized with 10 % PVA as the stabilizing agent had highest percentage of transparency among all the synthesized powder.
4,000원
6.
2013.08
구독 인증기관 무료, 개인회원 유료
Recently, products that a have 3-dimensional(3D) micro structure have been in wide use. To fabricate these 3D micro structures, several methods, such as stereo lithography, reflow process, and diffuser lithography, have been used. However, these methods are either very complicated, have limitations in terms of patterns dimensions or need expensive components. To overcome these limitations, we fabricated various 3D micro structures in one step using a pair of diffusers that diffract the incident beam of UV light at wide angles. In the experiment, we used positive photoresist to coat the Si substrate. A pair of diffusers(ground glass diffuser, opal glass diffuser) with Gaussian and Lambertian scattering was placed above the photomask in the passage of UV light in the photolithography equipment. The incident rays of UV light diffracted twice at wider angles while passing through the diffusers. After exposure, the photoresist was developed fabricating the desired 3D micro structure. These micro structures were analyzed using FE-SEM and 3D-profiler data. As a result, this dual diffuser lithography(DDL) technique enabled us to fabricate various microstructures with different dimensions by just changing the combination of diffusers, making this technology an efficient alternative to other complex techniques.
4,000원
7.
2013.08
구독 인증기관 무료, 개인회원 유료
Controlling the stick and slip motions of the contact lines in a confined geometry comprised of a spherical lens with a flat substrate is useful for manufacturing polymer ring patterns. We used a sphere on a flat geometry, by which we could control the interfaces of the solution, vapor and substrate. By this method, hundreds of concentric ring-pattern formations of a linear conjugated polymer, poly [2-methoxy-5-(2-thylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV), were generated with excellent regularity over large areas after complete solvent evaporation. Subsequently, the MEH-PPV ring patterns played a role as a directed template to organize highly regular concentric rings of single-walled carbon nanotubes(SWCNTs); when a droplet of the SWCNT suspension in water was casted onto the prepared substrate, hydrophobic polymer patterns confined the water dispersed SWCNTs in between the hydrophilicized SiO2/Si substrate. As the solvent evaporated, SWCNT-rings were formed in between MEH-PPV rings with controlled density. Finally, we used a lift-off process to produce SWCNT patterns by the removal of a sacrificial polymer template with organic solvent. We also fabricated a field effect transistor using self-assembled SWCNT networks on a SiO2/Si substrate.
4,000원
8.
2013.08
구독 인증기관 무료, 개인회원 유료
We study and describe-from the point of view of the interactions of the adsorbed particles-three types of the adsorption isotherms, namely, Langmuir type adsorption isotherms, phase transition type adsorption isotherms, and adsorption limited type adsorption isotherms, which are observed by experiments. By introducing and using a one dimensional statistical occupancy model, we derived analytical adsorption isotherms for the no force, the attractive force, and the repulsive force exerted on the other adsorbed particles. Our derived adsorption isotherms qualitatively pretty well agree with the experimental results of the adsorption isotherms. To specify each adsorption type, Langmuir type adsorption is a phenomenon that occurs with no forces between the adsorbed particles, phase transition type adsorption is a phenomenon that occurs with the strong attractive forces between the adsorbed particles, and adsorption limited type adsorption is a phenomenon that occurs with the repulsive forces between the adsorbed particles. The theoretical analysis-only using fundamental thermodynamics and occupancy statistics though-qualitatively quite well explains the experimental results.
4,000원
9.
2013.08
구독 인증기관 무료, 개인회원 유료
Al-doped ZnO(AZO) thin films were synthesized using atomid layer deposition(ALD), which acurately controlledthe uniform film thickness of the AZO thin films. To investigate the electrical and optical properites of the AZO thin films,AZO films using ALD was controlled to be three different thicknesses (50nm, 100nm, and 150nm). The structural, chemical,electrical, and optical properties of the AZO thin films were analyzed by X-ray diffraction, X-ray photoelectron spectroscopy,field-emssion scanning electron microscopy, atomic force microscopy, Hall measurement system, and UV-Visspectrophotometry. As the thickness of the AZO thin films increased, the crystallinity of the AZO thin films gradually increased,and the surface morphology of the AZO thin films were transformed from a porous structure to a dense structure. The averagesurface roughnesses of the samples using atomic force microscopy were ~3.01nm, ~2.89nm, and ~2.44nm, respectively. Asthe thickness of the AZO filmsincreased, the surface roughness decreased gradually. These results affect the electrical and opticalproperties of AZO thin films. Therefore, the thickest AZO thin films with 150nm exhibited excellent resistivity (~7.00×10−4Ω·cm), high transmittance (~83.2%), and the best FOM (5.71×10−3Ω−1). AZO thin films fabricated using ALD may be usedas a promising cadidate of TCO materials for optoelectronic applications.
4,000원
